One of the most important principles for the initial resuscitation of a head trauma patient is to promptly identify and surgically evacuate traumatic intracranial hematomas. Hematoma is a condition by which blood accumulates outside blood vessel generally as a result of a hemorrhage or trauma. Unilateral hematoma exists when blood accumulation takes place in one side of the head. Bilateral hematoma exists when blood accumulation exists in both sides of the head.
Time is crucial as the expanding mass lesion can cause death from brainstem compression or cause global ischemic injury. At least one study has shown that a delay of more than 4 hours between injury and the evacuation of a subdural hematoma increased mortality and worsened outcome in survivors.
CT scanning is one means for identifying and localizing localization traumatic intracranial hematomas. Achieving evacuation of intracranial hematomas in 4 hours generally requires an organized system of regional trauma centers, where a patient is initially taken to a nearby trauma center capable of complete treatment of their injury. For those patients with neurological injuries, a CT scan, followed by surgery if necessary, is obtained immediately after the patient is hemodynamically stabilized. However, in emergencies involving trauma to the head in rural areas of the US, in underdeveloped areas of the world and, critically, in the battlefield, timely identification of patients that require surgery can be more difficult.
Moreover, comprehensive trauma centers with 24 hr/day CT scanning are not always immediately available. The primary method for identification of patients with hematomas in these settings is the neurological exam. However, the neurological examination is a poor substitute for CT scan because no single physical sign reliably indicates the presence of a hematoma. Focal neurological findings are found in only a fraction of patients with surgical hematomas. Coma has been reported to occur without the occurrence of a surgical hematoma in 56% of patients with severe head injury. Although patients with intracranial hematomas have increased intracranial pressure (ICP), papilledema is uncommon after head injury, occurring in only 3.5% in one study. A unilateral dilated pupil is commonly identified as one lateralizing sign when it occurs in a patient with a hematoma, but the presence of such a finding does not clearly identify the presence of a surgical hematoma since it is also found in a significant number of patients with diffuse brain injuries.
There is a need, therefore, for a non-invasive system that is capable of detecting intracranial hematoma in-situ following a traumatic brain injury. Such a system is needed that will allow the maximum possible comfort to patient and ease of use for the operator, while maximizing hematoma detection rate and minimizing false alarm rate. Even if the type of hematomas cannot be determined with certainty, the presence of any type of hematoma is the only information required in the field to triage a patient immediately to a hospital with neurosurgical diagnostic and operative capabilities.
It is known that an accumulation of extravascular blood absorbs more near infrared (NIR) light than the intravascular blood. This is attributable to a greater concentration of hemoglobin in the extravascular blood than in blood contained within vessels. Extravascular blood may also have a higher degree of oxygenation than intravascular blood. At certain wavelengths, blood with a higher degree of oxygenation absorbs a different quantity of NIR than blood with a lower degree of oxygenation. U.S. Pat. No. 5,954,053 entitled Detection of Brain Hematoma, which is hereby incorporated by reference as if set forth in its entirety herein, describes systems and methods for detection of brain hematoma based upon concentrations of blood in tissue.